>上面的图片是一个图像的地球没有水。我们知道,上面的图片是一个非常夸张的一个。* * * *形象的图片被夸大了,它是不准确的。它不显示地球的最大的特点,就是它的赤道隆起。这并不说明地球没有水。它不显示第二大地球表面的物理特性没有水,这是它的高大的山脉和深海海沟。相反,它是一个高度的夸张形象大地水准面之间的偏差(常数表面重力+离心潜力)和一个假想的扁椭球。山通常显示为萧条这张照片而不是山的岩石,山是非常大的水滴,低于平均密度。这可以使大地水准面是低于海平面在/山脉附近。海洋通常显示为提升地区这张照片因为岩石底层海洋是玄武岩,具有高于平均密度。 Look at the Himalaya in that image. They are blue, which means they are below the average geoid height. Look at the Java Trench. It is the very deepest red, which means well above the average geoid height. The Rocky Mountains are white, no different than the rest of the northern North America. The Alps are reddish, but not as red as is the eastern North Atlantic. The image does not represent anything close to what many say it represents. The image is interesting to those who know what the image portrays. The problem is that the image is so often described incorrectly. 
 **Comparison to a basketball** The difference between the Earth's equatorial and polar radii is about 21.385 km. The difference between the height of the highest mountain on the Earth above sea level and the Earth's deepest trench below sea level is about 19.777 km. Shrinking these down to the size of a basketball with a circumference of 29.5 inches (I used US units because that is what NBA regulations specify) shrinks the 21.385 km difference between the equatorial and polar radii to a mere 0.4 millimeters, shrinks the height of Mount Everest above sea level to 0.165 millimeters, and shrinks the depth Challenger Deep below sea level to 0.204 millimeters. A basketball is supposed to be round(ish). That the Earth's polar radius is 99.66% of its equatorial radius makes the Earth fairly "roundish". The roundness of the Earth is in line with the roundness of a billiard ball, and probably for a basketball. (While I did find roundness requirements for a billiard ball, I was unsuccessful in finding roundness requirements for a basketball.) What about smoothness? Basketballs are not smooth. They are intentionally designed with stipples (pebbles) and channels so as to make basketballs easier to handle. There are patents galore regarding the size, shape, and placement of those pebbles and channels. The pebbles are a bit higher than 0.17 millimeters and the channels are significantly deeper than 0.2 millimeters. The Earth is smoother than a basketball because basketballs are unsmooth by design.